                                               ["=" "type" "Class"]
                                               ["=" "title" "Main"]]]]]]]
 
-   [{:certname "foo" :name "ipaddress" :value "192.168.1.100"}
-    {:certname "bar" :name "ipaddress" :value "192.168.1.101"}
-    {:certname "baz" :name "ipaddress" :value "192.168.1.102"}]
+   #{{:certname "foo" :name "ipaddress" :value "192.168.1.100"}
+     {:certname "bar" :name "ipaddress" :value "192.168.1.101"}
+     {:certname "baz" :name "ipaddress" :value "192.168.1.102"}}
 
    ;; No matching resources
    ["and"
     ["=" "name" "ipaddress"]
     ["in" "certname" ["extract" "certname" ["select-resources"
                                             ["=" "type" "NotRealAtAll"]]]]]
-   []
+   #{}
 
    ;; No matching facts
    ["and"
     ["=" "name" "nosuchfact"]
     ["in" "certname" ["extract" "certname" ["select-resources"
                                             ["=" "type" "Class"]]]]]
-   []
+   #{}
 
    ;; Fact subquery
    ["and"

                                             ["=" "name" "uptime_seconds"]
                                             [">" "value" 10000]]]]]]

   [{:certname "foo" :name "ipaddress" :value "192.168.1.100"}]))

(def versioned-subqueries
  (omap/ordered-map

    ["in" "certname" ["extract" "certname" ["select-resources"
                                            ["=" "type" "Class"]]]]]

   #{{:certname "foo" :name "ipaddress" :value "192.168.1.100"}
     {:certname "bar" :name "ipaddress" :value "192.168.1.101"}
     {:certname "baz" :name "ipaddress" :value "192.168.1.102"}}

   ;; Multiple facts
   ["and"
